Lancing device with independent drive core

ABSTRACT

A medical lancing device including an independent drive core mechanism incorporating all or a substantial portion of the functional components of the lancing device, whereby the independent drive core mechanism can be incorporated into multiple different external housing configurations for more efficient design and manufacture. Axial adjustment of the position of the independent drive core mechanism within the housing provides lancing penetration depth control.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of U.S. Provisional PatentApplication Ser. No. 60/794,809 filed Apr. 25, 2006, and U.S.Provisional Patent Application Ser. No. 60/804,877 filed Jun. 15, 2006,both of which are hereby incorporated herein by reference in theirentirety for all purposes.

TECHNICAL FIELD

The present invention relates generally to a lancing device for medicalsampling of blood or other body fluids of a human or animal subject.

BACKGROUND OF THE INVENTION

Many medical procedures require puncturing of the skin, and sometimesunderlying tissues, of a human or animal subject. For example, a sharplancet tip is commonly used to prick the subject's skin at a lancingsite to obtain a sample of blood or other body fluid, as for example inblood glucose monitoring by diabetics and in blood typing and screeningapplications.

In order to obtain an adequate sample size with minimal or no pain tothe subject, it is often desirable to provide for adjustment of thedepth of penetration of the lancet tip into the subject's skin. Forexample, individuals with thicker skin or deeper capillaries may requirelancing to a deeper penetration depth than individuals having thinnerskin or shallower capillaries. Also, alternate site lancing, for exampleon the forearm or other body portion of the subject, rather thanfingertip sampling, may require a deeper penetration depth.

Common mechanisms for accomplishing depth adjustment include movablestop members for limiting the stroke of a lancet or lancet carrier, andadjustable endcaps for varying the position of the sampling siterelative to the forward extent of the lancet stroke. Some known depthadjustment mechanisms for lancing devices may contribute to thetransmission of an unacceptable degree of vibration to the lancing site,which may increase the perception of pain from the lancing procedure.Also, in many instances it may be desirable to provide a more preciseadjustment of penetration depth than some known depth adjust mechanismsprovide. Accordingly, it can be seen that continued improvement to depthcontrol in lancing devices is desirable.

Additionally, in the design of lancing devices it is often desirable toprovide a distinctive and unique product configuration to a lancingdevice, for purposes of product differentiation in the marketplace, foraesthetic and/or functional compatibility with related products such asblood glucose meters, and/or for branding purposes. For example, a firstsupplier may wish for their model of lancing device to have one shape,color scheme, etc., whereas a second supplier may wish for their modelof lancing device to have a different shape, color scheme, etc. Theexpense and time involved in designing and developing a commerciallyacceptable lancing device can be considerable. Accordingly, it can beseen that improvements to lancing devices and to design, development andmanufacturing methods for lancing devices that permit differentiation ofproducts more efficiently and economically is desirable.

It is to the provision of improved lancing devices, and to improveddesign, development and manufacturing methods for lancing devicesmeeting this and other needs that the present invention is primarilydirected.

SUMMARY OF THE INVENTION

In example embodiments, the lancing device of the present inventionincludes an independent drive core mechanism that is adaptable to use inconnection with a variety of external housing configurations. Adjustmentof the axial position of the independent drive core mechanism within theexternal housing allows precise depth adjustment in various forms of theinvention that are easy and intuitive for a user to operate. Moving theindependent drive core mechanism forward (toward the lancing site) inthe external housing generally results in a deeper penetration, whereasmoving the independent drive core mechanism rearward (away from thelancing site) in the external housing generally results in a shallowerpenetration.

Because the independent drive core mechanism of the present invention isrelatively compact and includes all or a substantial portion of thefunctional components of the lancing device, it can be efficientlyincorporated into different external housing configurations. Theindependent drive core mechanism thus provides a suitable off-the-shelfmechanism that a designer or manufacturer can utilize to streamline thedesign, development and production of lancing devices. In terms ofproduct differentiation between lancing devices of different suppliers,it has been discovered that it may be immaterial to both the user andthe supplier whether the internal mechanical workings of the lancingdevices are the same or different, so long as the end user perceives thedevices to be different from the outside. In such cases, it has beendiscovered that it will often be more efficient, both in terms ofmanufacturing cost and design lead-time, to utilize a common independentdrive core mechanism according to the present invention, which isadaptable for use with different external housing configurations.

In example embodiments, the external housing of a lancing deviceaccording to the present invention includes one or more components forinterfacing with the independent drive core mechanism so as to providepositional adjustment of the independent drive core mechanism within theexternal housing for depth control. In alternate embodiments, theindependent drive core mechanism is fixed in position in the externalhousing, resulting in a single depth lancing device. In still otherembodiments, the independent drive core mechanism is fixed in positionin the external housing, and the external housing includes another formof depth control mechanism.

In one aspect, the invention is a lancing device, preferably includingan external housing having a lancet opening, and an independent drivecore mechanism positioned at least partially within the externalhousing. The independent drive core mechanism includes a mechanismhousing; a drive plunger for receiving a lancet, the drive plunger beingtranslationally mounted for advancement and retraction within themechanism housing; a drive spring engaged between the mechanism housingand the drive plunger, for advancing the drive plunger toward the lancetopening; and a charging housing for retracting the drive plunger andenergizing the drive spring.

In another aspect, the invention is an independent drive core mechanismfor a lancing device. The independent drive core mechanism preferablyincludes a mechanism housing having a bore extending axiallytherethough; a drive plunger having a receiver for releasably engaging alancet, the drive plunger being translationally mounted for advancementand retraction within the bore of the mechanism housing between anadvanced position and a retracted position; a drive spring engagedbetween the mechanism housing and the drive plunger, for advancing thedrive plunger toward the advanced position; a charging housing forretracting the drive plunger and energizing the drive spring; and atleast one retention member for engagement with a cooperating portion ofan external housing.

In still another aspect, the invention is a drive mechanism forinstallation within a lancing device housing. The drive mechanismpreferably includes a mechanism housing, a drive plunger movable betweenan advanced position and a retracted position relative to the mechanismhousing, wherein a constant stroke of travel is defined between theadvanced position and the retracted position, and a drive spring engagedbetween the mechanism housing and the drive plunger to propel the driveplunger along the stroke of travel. Optionally, a depth-adjust mechanismvaries the position of the constant stroke length drive mechanism withina lancing device housing to provide lancing penetration depthadjustment.

In another aspect, the invention is a method of designing lancingdevices, the method preferably including specifying an independent drivecore mechanism having a mechanism housing, a lancet carriertranslationally mounted within the mechanism housing, a drive spring foradvancing the lancet carrier, and a return spring for retracting thelancet carrier. The method preferably further includes specifying thedesign of a first lancing device incorporating the independent drivecore mechanism into a first external housing configuration, andspecifying the design of a second lancing device incorporating theindependent drive core mechanism into a second external housingconfiguration different from the first external housing configuration.

In another aspect, the invention is a method of manufacturing lancingdevices, the method preferably including providing an independent drivecore mechanism having a mechanism housing, a lancet carriertranslationally mounted within the mechanism housing, a drive spring foradvancing the lancet carrier, and a return spring for retracting thelancet carrier. The method preferably further includes assembling afirst lancing device by installation of the independent drive coremechanism into a first external housing configuration, and assembling asecond lancing device by installation of the independent drive coremechanism into a second external housing configuration different fromthe first external housing configuration.

These and other aspects, features and advantages of the invention willbe understood with reference to the drawing figures and detaileddescription herein, and will be realized by means of the variouselements and combinations particularly pointed out in the appendedclaims. It is to be understood that both the foregoing generaldescription and the following brief description of the drawings anddetailed description of the invention are exemplary and explanatory ofpreferred embodiments of the invention, and are not restrictive of theinvention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a mechanical drive core portion of alancing device according to an example form of the present invention.

FIG. 2 a is a cross-sectional side view of the mechanical drive core ofFIG. 1, shown in a loading state.

FIG. 2 b is a side view of the mechanical drive core of FIG. 1, shown inthe loading state.

FIG. 3 a is a cross-sectional side view of the mechanical drive core ofFIG. 1, shown in a neutral state.

FIG. 3 b is a side view of the mechanical drive core of FIG. 1, shown inthe neutral state.

FIG. 4 a is a cross-sectional side view of the mechanical drive core ofFIG. 1, shown in a charging state.

FIG. 4 b is a side view of the mechanical drive core of FIG. 1, shown inthe charging state.

FIG. 5 a is a cross-sectional side view of the mechanical drive core ofFIG. 1, shown in a charged state.

FIG. 5 b is a side view of the mechanical drive core of FIG. 1, shown inthe charged state.

FIG. 6 a is a cross-sectional side view of the mechanical drive core ofFIG. 1, shown in an activated state.

FIG. 6 b is a side view of the mechanical drive core of FIG. 1, shown inthe activated state.

FIG. 7 a is a cross-sectional side view of the mechanical drive core ofFIG. 1, shown in an ejection state.

FIG. 7 b is a side view of the mechanical drive core of FIG. 1, shown inthe ejection state.

FIG. 8 a is a perspective view of the mechanical drive core of FIG. 1,shown in a charged or pre-ejection state.

FIG. 8 b is a cross-sectional perspective view of the mechanical drivecore of FIG. 1, shown in a charged or pre-ejection state.

FIG. 9 a is a perspective view of the mechanical drive core of FIG. 1,shown in the ejection state.

FIG. 9 b is a cross-sectional perspective view of the mechanical drivecore of FIG. 1, shown in the ejection state.

FIGS. 10 a, 10 b and 10 c show a sequence of depth-adjustment positionsof the mechanical drive core within a lancing device having a first typeof outer housing.

FIGS. 11 a, 11 b and 11 c show a sequence of depth-adjustment positionsof the mechanical drive core within a lancing device having a secondtype of outer housing.

FIG. 12 is an assembly view showing the single-axis assembly of a drivecore mechanism according to another embodiment of the invention.

FIGS. 13 a and 13 b show a step of the assembly sequence of the drivecore mechanism of FIG. 12, according to an example form of theinvention.

FIGS. 14 a and 14 b show a subsequent step of the assembly sequence.

FIGS. 15 a, 15 b and 15 c show a subsequent step of the assemblysequence.

FIGS. 16 a and 16 b show a subsequent step of the assembly sequence.

FIGS. 17 a and 17 b show a subsequent step of the assembly sequence.

FIG. 18 shows a subsequent step of the assembly sequence.

FIGS. 19 a and 19 b show a subsequent step of the assembly sequence.

FIGS. 20 a, 20 b and 20 c show a subsequent step of the assemblysequence.

FIGS. 21 a and 21B show perspective and cross-sectional views of a drivecore mechanism according to another embodiment of the invention.

FIG. 22 shows a lancing device incorporating the drive core mechanism ofFIG. 21 mounted in an external housing, according to another form of theinvention.

FIG. 23 shows a lancing device and drive core mechanism according toanother embodiment of the invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The present invention may be understood more readily by reference to thefollowing detailed description of the invention taken in connection withthe accompanying drawing figures, which form a part of this disclosure.It is to be understood that this invention is not limited to thespecific devices, methods, conditions or parameters described and/orshown herein, and that the terminology used herein is for the purpose ofdescribing particular embodiments by way of example only and is notintended to be limiting of the claimed invention. Also, as used in thespecification including the appended claims, the singular forms “a,”“an,” and “the” include the plural, and reference to a particularnumerical value includes at least that particular value, unless thecontext clearly dictates otherwise. Ranges may be expressed herein asfrom “about” or “approximately” one particular value and/or to “about”or “approximately” another particular value. When such a range isexpressed, another embodiment includes from the one particular valueand/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another embodiment.

With reference to FIGS. 1-9, an independent drive core mechanism 10 fora lancing device is shown according to an example form of the invention.The independent drive core mechanism 10 is preferably compact, and inthe depicted embodiment has a generally cylindrical, narrow-profile,elongate outer geometry, for example having an aspect ratio(length:diameter) of at least 3:1. The independent drive core mechanism10 generally comprises a mechanism housing 20 having a bore extendingaxially therethough; a drive plunger 40, a charging housing 60, and anejector rod 80. A drive spring 90 is engaged between the mechanismhousing 20 and the drive plunger 40, a return spring 100 is engagedbetween the drive plunger 40 and the charging housing 60, and an ejectorspring 110 is engaged between the ejector rod 80 and the mechanismhousing 20.

The mechanism housing 20 is a generally cylindrical sleeve having awider proximal cylindrical section 22 at a first end, a narrower distalcylindrical section 24 at a second end thereof, and a tapering conicalsection 26 therebetween. An inwardly and outwardly projecting flange 28extends from the second end of the mechanism housing 20, for engagementwith a distal end of the drive spring 90 (on the forward face of theinwardly directed portion of flange 28), and with a proximal end of theejector spring 110 (on the rear face of the outwardly directed portionof flange 28), when the independent drive core mechanism is assembled.The mechanism housing 20 is generally hollow, having an internal boreextending axially from the first end to the second end. Astroke-limiting slot 30 extends axially lengthwise through a lateralsidewall portion of the mechanism housing 20, along portions of thedistal cylindrical section 24 and the conical section 26 thereof. Aresiliently flexing finger 32 has a free end defining the proximal endof the stroke-limiting slot 30. The finger 32 flexes outwardly duringassembly to allow installation of the drive plunger 40 into themechanism housing 20. A trigger slot 34 extends axially lengthwisethrough an upper sidewall portion of the mechanism housing 20, alongportions of the proximal cylindrical section 22, the distal cylindricalsection 24, and the conical section 26 thereof. A shoulder or othercatch member 35 projects into or adjacent the trigger slot 32. A channelor other guide member 36 extends axially along a lateral exteriorsidewall of the mechanism housing 20, and an outwardly projecting memberor lug 38 extends from an upper sidewall of the mechanism housing. Theguide member 36 and/or the lug 38 serve as retention members forengagement with a cooperating portion of an external housing into whichthe independent drive core mechanism 10 is installed.

The drive plunger 40 is translationally mounted within the axiallyextending bore of the mechanism housing 20 for advancement andretraction between an advanced position and a retracted position. Thedrive plunger 40 includes a cup-shaped holder or receiver 42 at itsproximal end for releasably engaging a lancet L of standard orcustomized configuration. The receiver 42 preferably retains the lancetwith a friction fit, for example by means of a slotted cylindricalsidewall formed of resiliently flexible material, and having an internaldimension in its relaxed state of slightly less than the outer dimensionof the lancet, such that the slotted sleeve flexes slightly and expandsto frictionally receive the lancet upon insertion with light manualforce. An axially elongate tube portion 44 of the drive plunger 40extends distally from the receiver 42, and through an opening in theinwardly directed portion of the flange 28 at the distal end of themechanism housing 20. The tube portion 44 of the drive plunger 40defines an inner bore along its entire length, opening at its proximalend into the receiver, and also open at its distal free end. A tailportion 46 of the tube portion 44 of the drive plunger 40 has anexpanded outer diameter or flared portion for engagement with a distalend of the return spring 100, which is coiled about the exterior of thetube portion of the drive plunger within the charging housing. The tailportion 46 is split along its length to permit the opposed side portionsthereof to be flexed inwardly toward one another to receive the returnspring 100 thereon and for assembly into the mechanism housing 20 andthe charging housing 60. The drive spring 90 is coiled about the tubeportion 44 of the drive plunger 40, within the mechanism housing 20. Oneor more laterally projecting wings 48 extend from an outer face of thedrive plunger 40, and slide within the stroke-limiting slot 30 of themechanism housing 20 to define the stroke of travel of the drive plungerrelative to the mechanism housing. Contact between the wing(s) 48against the finger 32 at the proximal end of the stroke-limiting slot 30defines the advanced position of the drive plunger 40, and contactbetween the wing(s) against the distal end of the stroke-limiting slotdefines the retracted position of the drive plunger. In this manner, aconstant stroke distance of the drive plunger and the lancet carriedtherein is provided. Engagement of the wing(s) 48 within thestroke-limiting slot 30 also serves to prevent twisting of the driveplunger 40 relative to the mechanism housing 20. During assembly, thewings 48 cause the cantilevered finger 32 to flex outwardly as the driveplunger is installed into the mechanism housing, and the finger springsback after the wings have passed into the slot 30 to retain the driveplunger in place within the mechanism housing. A flexible trigger arm 50extends in cantilevered fashion outwardly from the drive plunger 40, andis received in the trigger slot 34 of the mechanism housing 20. The freeend of the trigger arm 50 releasably engages against the shoulder orcatch member 35 of the trigger slot 34 of the mechanism housing 20 toretain the drive plunger 40 in its charged state until released by theuser. The trigger arm 50 also engages a proximal end of the drive spring90 as the drive plunger 40 is retracted during charging to compress andenergize the drive spring. A guide flange or finger 52 extends from thedrive plunger 40 for sliding engagement against an interior guidesurface of the mechanism housing 20 to constrain the drive plunger toaxial linear translational movement and substantially prevent lateralmovement, thereby providing a smooth and linear path of travel to thelancet as it moves along its lancing stroke.

The charging housing 60 is a generally cylindrical, elongate tubularmember having an inwardly directed flange 62 at its proximal end and anoutwardly directed flange 64 at its distal end. The forward face of theinwardly directed flange 62 confronts the rear face of flange 28 of themechanism housing, and the rear face of the inwardly directed flange 62engages a proximal end of the return spring 100, when assembled. Adiametrically opposed pair of slots 66 a, 66 b extends along thecharging housing 60 from its distal end. As seen best with reference toFIGS. 8 and 9, distal portions of each of the slots 66 a, 66 b extend ina generally axial direction along the sidewalls of the charging housing60, angularly slanted or helically curved medial portions of the slotsextend proximally from the distal portions of the slots, and proximalportions of the slots extend generally axially forward from theangularly or helically oriented medial portions of the slots, wherebythe distal and proximal portions of the slots are generally parallel butangularly offset by about 50° from one another. The distal portions ofeach of the slots 66 a, 66 b are relatively narrow, and the medial andproximal portions of the slots are relatively wide, such that pinretention pockets 68 a, 68 b are formed at the intersection of thedistal and medial portions of the slots. The ejector spring 110 iscoiled about the external surface of the charging housing 60. One ormore channels 70 a, 70 b serve as rear retention members for engagementwith an ejection interface or other cooperating portion of an externalhousing into which the drive core 10 is installed, to secure the drivecore within the housing, maintain proper alignment during depthadjustment, and prevent the drive core from twisting relative to thehousing.

The ejector rod 80 comprises an elongate cylindrical rod 82 having anouter diameter configured to slide smoothly within the inner bore of thetube portion 44 of the drive plunger 40, and a tapered proximal end. Theejector rod 80 further comprises a generally circular flange 84 at thedistal end of the cylindrical rod 82, having a diameter configured toslide smoothly within the inside channel of the charging housing 60. Apair of diametrically opposed pins or fingers 86 a, 86 b extendoutwardly from the flange 84, and are received within the slots 66 a, 66b of the charging housing 60, such that when assembled the fingers 86 a,86 b can freely slide within the slots between the retention pockets 68a, 68 b and the proximal ends of the slots. Outer ends of the fingers 86a, 86 b engage the distal end of the ejector spring 110. A stop or rib88 extends laterally from a side face of the cylindrical rod 82 forabutment against a shelf or shoulder at the rear face of the tailportion 46 of the tube portion 44 of the drive plunger 40 to preventinadvertent ejection of a lancet by advancement of the ejector rod 80when the drive plunger is in its charged position (FIG. 8 b).

Product Differentiation with Common Drive Core

FIGS. 10 and 11 show assembly of an independent drive core mechanism 10,as described above, into two different forms of lancing devices 200,200′ according to example embodiments of the invention. When it isstated herein that different forms of lancing devices incorporate acommon independent drive core mechanism, it is not intended that thespecific independent drive core mechanism unit be installed in each formof lancing device, but rather that different independent drive coremechanism units having a substantially common design may be installed inthe different forms of lancing devices.

In the embodiment of FIG. 10, an independent drive core mechanism 10 isinstalled within a first form of external housing 202, whereas in theembodiment of FIG. 11, the same type of independent drive core mechanism10 is installed within a second form of external housing 202′ that isdifferent from the first external housing. For example, the embodimentof FIG. 10 includes a first type of trigger release button 204, whereasthe embodiment of FIG. 11 includes a different type of trigger releasebutton 204′; and a knurled ring 206 is present on the embodiment of FIG.11, but not on the embodiment of FIG. 10. In those embodiments of thelancing device of the present invention that provide lancing depthadjustment by means of varying the axial position of the drive corewithin the external housing, the trigger release button preferablyincludes or is coupled to an elongate fin that extends a sufficientaxial span to contact the free end of the trigger arm 50 regardless ofthe position of the drive core within the housing. By sharing a commondesign of the independent drive core mechanism 10 between two or moredifferent forms of lancing devices, product differentiation anddifferent modes of product usage may be accomplished with improvedefficiencies, as compared to previous methods of design, development andmanufacture of lancing devices.

Because the internal workings of the lancing device are common to theirshared independent drive core mechanisms, the independent drive coremechanism can be considered an off-the-shelf assembly, available foradaptation and use in a variety of different forms of lancing devices.Design, development and manufacturing costs and lead times may bereduced, because only the external housing and drive core mechanisminterfaces (e.g., trigger-release interface, depth-adjust interface,charging interface, and/or ejection interface) will differ significantlybetween the different forms of lancing devices. Also, economies of scalemay be improved by the provision of a common independent drive coremechanism adaptable for use in multiple forms of lancing devices.

For example, in the design of lancing devices, the present inventionprovides a method of designing lancing devices wherein a designerspecifies a common independent drive core mechanism 10 such as thatdescribed above. The same or a different designer further specifies thedesign of a first lancing device incorporating the common independentdrive core mechanism into a first external housing configuration. Thesame or a different designer further specifies the design of a secondlancing device incorporating the common independent drive core mechanisminto a second external housing configuration different from the firstexternal housing configuration. The first and second lancing devicedesigns are distinguishable in terms of their manner of operation and/ortheir external appearance or configuration, despite sharing asubstantially common internal drive core mechanism.

In the manufacture of lancing devices, the present invention provides amanufacturing method wherein a common independent drive core mechanismsuch as that described above is assembled into a first lancing device byinstallation of the independent drive core mechanism into a firstexternal housing configuration. The same or a different manufacturerassembles a second lancing device by installation of the commonindependent drive core mechanism into a second external housingconfiguration different from the first external housing configuration.The first and second lancing devices are distinguishable in terms oftheir manner of operation and/or their external appearance orconfiguration, despite sharing a substantially common internal drivecore mechanism.

Depth Adjustment

The independent drive core mechanism 10 is optionally mounted within theexternal housing 202, 202′ in an axially adjustable manner, whereby theuser may selectively control the lancing depth by varying the axialposition of the independent drive core mechanism forward (proximally) orback (distally) within the external housing. In its various forms, theinterior structure of the external housing preferably includes one ormore guidance surfaces for interfacing with cooperating guidanceportions of the independent drive core mechanism, to restrict transversemovement and provide smooth axial movement of the independent drive coremechanism within the housing.

For example, in the embodiment of FIGS. 10 a, 10 b and 10 c, a linearlyactuated actuator 210 is moved axially forward and back to vary theposition of the independent drive core mechanism forward and back withinthe external housing 202, between a shallow penetration depth setting(FIG. 10 a), a medium penetration depth setting (FIG. 10 b), and a deeppenetration depth setting (FIG. 10 c). Multiple discrete indexed depthsettings can be provided, or the depth adjustment can be continuouslyvariable between the shallow and deep settings. Indicia can be providedon the housing to specify the depth setting. Moving the independentdrive core mechanism forward within the external housing 202 (toward theproximal end of the housing containing the lancet opening 212) resultsin a deeper lancing penetration, whereas moving the independent drivecore mechanism rearward within the housing results in a shallowerlancing penetration. The linearly actuated actuator 210 is preferablyslidably coupled within an inclined or arcuate slot 212 in adepth-adjust linkage 214, which is in turn linked to a depth-adjustcollar 216 having a slot 218, which engages the lug 38 on the mechanismhousing 20 of the independent drive core mechanism 10. The slot 218 ofthe depth-adjust collar 216 preferably has a relatively smaller pitch orangle of inclination than the slot 212 of the depth-adjust linkage 214,such that a larger adjustment of the position of the actuator 210results in a finer degree of adjustment of the penetration depth,thereby providing more precise depth adjustment.

In the embodiment of FIGS. 11 a, 11 b and 11 c, a rotary actuatedactuator 230 is moved circumferentially side to side to vary theposition of the independent drive core mechanism 10 forward and backwithin the external housing 202′, in a manner similar to that describedabove, between a shallow penetration depth setting (FIG. 11 a), a mediumpenetration depth setting (FIG. 11 b), and a deep penetration depthsetting (FIG. 11 c). The actuator extends through the shell of theexternal housing, and is linked to a depth-adjust collar 232 having aslot 234, which engages the lug 38 on the mechanism housing 20 of theindependent drive core mechanism 10 to adjust the axial positioning ofthe independent drive core mechanism within the external housing.

Assembly of the Independent Drive Core Mechanism

FIGS. 12-20 show a sequence of assembly of a substantially similar drivecore mechanism 10′ according to an example form of the invention. Asseen best with reference to FIG. 12, the components of the drive coreare assembled linearly along a single axis A. Simplicity ofmanufacturing is further enhanced by a mechanism design incorporatingonly four molded components (typically plastic components), and threesprings (typically metal coil springs), and requiring minimal or nomanipulation of unconstrained springs under compression during assembly.

FIGS. 13 a and 13 b show installation of the drive spring 90′ onto thedrive plunger 40′. The slotted tail end of the drive plunger flexesinwardly to receive the drive spring, and then expands to retain thedrive spring thereon. Inclined distal faces of the tail end of the driveplunger are optionally provided for ease of assembly of the drive springonto the drive plunger.

The assembled drive plunger 40′ and drive spring 90′ are then insertedaxially into the mechanism housing 20′, as shown in FIGS. 14 and 15. Thelaterally projecting wings of the drive plunger cause the resilientfingers of the mechanism housing to flex outwardly, and then snap backto retain the drive plunger within the mechanism housing. The slottedtail end of the drive plunger flexes inwardly again to fit through thedistal end of the mechanism housing, causing the drive spring to actbetween the inside face of the distal end of the mechanism housing andthe “wings” on the drive plunger.

The ejection spring 110′ is then installed onto the outside of thecharging housing 60′, as shown in FIGS. 16 a and 16 b. The distal flangeof the charging housing retains the ejection spring in place on thecharging housing. The assembly of the charging housing 60′ and ejectionspring 110′ is then placed over the tail end of the drive plunger 40′,as shown in FIGS. 17 a and 17 b, with the opposed sides of the splittail of the drive plunger flexing inward to allow entry through a holein the proximal flange of the charging housing, and then snapping backto prevent removal.

The drive plunger 40′ is retracted within the mechanism housing 20′,into its charged configuration, with the drive spring 90′ compressed andenergized, and the trigger arm of the drive plunger engaged, as shown inFIG. 18. The return spring 100′ is then inserted into the distal end ofthe charging housing 60′ as shown in FIG. 19 a, and onto the tail end ofthe drive plunger 40′ as shown in FIG. 19 b. Engagement of the returnspring 100′ between the flared portion of the drive plunger tail and theinward proximal flange of the charging housing couples the charginghousing to the drive plunger and mechanism housing assembly.

The ejector rod 80′ is then inserted into the distal end of the charginghousing, as shown in FIGS. 20 a-20 c. The pins of the ejector rod arepreferably thicker than the distal portions of the slots of the charginghousing, such that installation of the ejector rod flexes the slotsapart to receive the pins, and the charging housing snaps back as thepins enter the pin retention pockets or the wider medial portions of theslots, to retain the ejector rod within the charging housing.

Use of the Lancing Device

In use, a lancet L is loaded into the receiver 42 of the drive plunger40, as shown in FIGS. 2 and 3. The depth-adjustment mechanism, ifpresent, may be set to the desired lancing penetration depth, accordingto its specified manner of operation, for example as described abovewith reference to FIGS. 10 and 11.

Pulling the charging housing 60 distally away from the mechanism housing20 compresses the return spring 100 between the expanded portion of thetail 46 of the drive plunger 40 and the rear face of flange 62 of thecharging housing. As the return spring 100 reaches its fully compressedstate, further retraction of the charging housing 60, as seen in FIG. 4,pulls the drive plunger 40 rearward within the mechanism housing 20,compressing and energizing the drive spring 90, until wing 48 of thedrive plunger contacts the distal end of the slot 30 in the mechanismhousing, and the free end of the trigger arm 50 clears the shoulder orcatch member 35 of the trigger slot 32, in the retracted position of thedrive plunger.

Upon release of the charging housing 60, the return spring 100 extendsto move the charging housing back against the mechanism housing 20. Thedrive plunger 40 is retained in its charged state by the engagement ofthe free end of the trigger arm 50 with the shoulder or catch member 35,resisting the bias of the compressed drive spring 90. FIG. 5 shows theindependent drive core mechanism 10 in this charged or energized state.In this state, the rib 88 of the ejector rod is in alignment with thetail 46 of the retracted drive plunger 40, and the drive plunger therebyblocks forward advancement of the ejector rod to prevent inadvertentejection of the lancet L from the receiver 42 of the drive plunger.

The lancing device is then placed with its lancet opening 212, 212′against the desired lancing site of a human or animal subject. Therelease button 204, 204′ is actuated to release the trigger arm 50 fromengagement with the shoulder or catch member 35, allowing the drivespring 90 to propel the drive plunger 40 and the lancet L engagedtherein forward or proximally, into its advanced position as shown inFIG. 6, wherein a sharp tip of the lancet projects a distance outwardlyfrom the lancet opening to penetrate the subject's skin at the lancingsite. The drive spring 90 is sufficiently stronger than the returnspring 100 to propel the drive plunger through its lancing stroke.Contact of the wing 48 of the drive plunger against the proximal end ofthe slot 30 in the mechanism housing limits the forward travel of thedrive plunger. After the lancing stroke is completed, the drive spring90 and return spring 100 reach equilibrium at a neutral position of thedrive plunger (FIGS. 2 and 7).

FIGS. 7-9 show the ejection sequence, whereby the used lancet L isejected from the receiver 42 of the drive plunger 40 by actuation of theejection actuator 208 of the lancing device. In the neutral state of thedrive plunger 40, the ejector rod 80 may be advanced. As the pins 86 a,86 b of the ejector rod 80 traverse the angled or arcuate medialportions of the slots 66 a, 66 b of the charging housing 60, the ejectorrod twists, moving the rib 88 of the ejector rod out of alignment withthe shelf or shoulder on the rear face of the tail 46 of the driveplunger 40, and into alignment with the slot of the drive plunger'stail. Comparing FIGS. 8 and 9, it can be seen that abutment of the rib88 with the shoulder of the tail 46 blocks advancement of the ejectorrod in the charged position (FIG. 8), whereas alignment of the rib 88with the slot of the drive plunger's tail allows advancement of theejector rod in the neutral position (FIG. 9). The cylindrical ejectionrod 82 extends through the inner bore of the tube portion 44 of thedrive plunger 40, through the tube's proximal end and into the receiver42 (see FIG. 7), where it dislodges the lancet L from the receiver. Thefree end of the trigger arm 50 abuts a forward shoulder of the slot 34in the ejection state (see FIG. 7 a), to prevent the drive plunger frommoving forward as the ejection rod presses against the back of thelancet. Advancing the ejection rod causes the pins 86 a, 86 b tocompress the ejector spring 110 (see FIGS. 7 and 9), and upon release ofthe ejection actuator after lancet removal the ejector spring 110expands to return the ejection rod to its retracted position. Afterremoval, the used lancet is disposed of and the lancing device is readyfor reuse.

Alternate Embodiments

While the invention has been described with reference to preferred andexample embodiments, it will be understood by those skilled in the artthat a variety of modifications, additions and deletions are within thescope of the invention, as defined by the following claims.

For example, FIGS. 21 and 22 depict a drive core mechanism 310 andlancing device 312 according to an embodiment of the invention similarto that described above, but omitting the ejection and chargingsubassemblies. The drive core mechanism 310 includes a mechanism housing320, a drive plunger 340, a drive spring 390, and a return spring 400,all substantially similar to corresponding components of the drive coremechanism 10 described above. Omission of the ejection and chargingsubassemblies results in a shorter overall mechanism, allowing use of amore compact outer housing 410. In this form of the invention, the usermanually charges the drive mechanism by pushing the lancet L distallyupon insertion, and manually removes the lancet by pulling it from thereceiver 342 after use.

FIG. 23 shows a lancing device 500 having an independent drive coremechanism or chassis 510 according to another embodiment of theinvention. In this embodiment, the drive plunger 540 comprises a colletreceiver having a plurality of flexing fingers that are opened bycontact with the proximal end of the ejection rod 580 to release thelancet L during ejection upon pressing the ejection actuator 581. A stop555 on the drive plunger contacts a cooperating flange or shoulder ofthe chassis housing 520 to limit the stroke of the drive plunger withinthe chassis. A rotationally mounted depth control ring portion 575 ofthe external housing 577 is coupled to a collar 579 having a helicalslot engaging a pin or lug of the housing 520 to advance and retract thedrive core mechanism 510 axially within the housing for lancingpenetration depth adjustment. The release button 595 of the externalhousing includes an elongate fin for interfacing with a ring trigger 597that deforms to selectively engage and release a flared catch portion541 of the drive plunger 540. A coupling 533 may allow a degree offreedom along a short axial distance between the drive plunger 540 andthe return plunger 535, to reduce transmission of vibration to thelancet for reduced pain, and/or to minimize the need for holding springsin compression during assembly. The drive spring 590 is located axiallyforward of the trigger release 595 to reduce vibration and lateralmovement of the lancet during the lancing stroke. The return spring 600and ejector spring 610 are positioned in the charging housing 560, whichis coupled to a retractable charging actuator 565 of the externalhousing. A mechanism lock comprising a spring arm 545 (shown inalternate forms as 545 a and 545 b) engages the return plunger 535 tolock the drive core mechanism in position when the endcap 525 is removedfrom the external housing, to prevent inadvertent launching of a lancet,and for easier insertion and removal of the lancet. A flange 527 of theendcap interacts with a lock release 547 (shown in alternate forms as547 a and 547 b) to release the spring arm from the return plunger whenthe endcap is installed on the housing, allowing movement of the drivecore mechanism.

1. A lancing device comprising: an external housing comprising a lancetopening; and an independent drive core mechanism positioned at leastpartially within the external housing, said independent drive coremechanism comprising: a mechanism housing comprising a proximal end, adistal end, and a sidewall portion between the proximal and distal endshaving a stroke-limiting slot formed therethrough; a drive plunger forreceiving a lancet, said drive plunger translationally mounted foradvancement and retraction within the mechanism housing, said driveplunger further comprising a laterally projecting wing extendingtherefrom and sliding axially within the stroke-limiting slot of themechanism housing when the drive plunger advances and retracts withinthe mechanism housing; an ejector rod axially movable and rotatablethrough a bore in the drive plunger, for ejecting a lancet from thedrive plunger; a drive spring engaged between the mechanism housing andthe drive plunger, for advancing the drive plunger toward the lancetopening; and a charging handle for retracting the drive plunger andenergizing the drive spring, wherein the ejector rod comprises at leastone finger extending through a generally helical slot in the charginghandle.
 2. The lancing device of claim 1, wherein a flexible armextending from the drive plunger releasably engages a shoulder of themechanism housing to retain the drive plunger in a retracted positionagainst the bias of the drive spring.
 3. The lancing device of claim 1,wherein the independent drive core mechanism is selectively positionablewithin the external housing to provide lancing depth adjustment.
 4. Thelancing device of claim 3, wherein the mechanism housing comprises atleast one guide for sliding engagement with a cooperating portion of theexternal housing to constrain the independent drive core mechanism tolinear translational motion within the external housing.
 5. The lancingdevice of claim 3, wherein the mechanism housing comprises an outwardlyprojecting member for engagement with a depth-adjustment element of theexternal housing.
 6. The lancing device of claim 5, wherein thedepth-adjustment element of the external housing comprises arotationally mounted collar having a cam slot therein for receiving theoutwardly projecting member of the mechanism housing, such that rotationof the collar advances and retracts the independent drive core mechanismwithin the external housing.
 7. The lancing device of claim 1 furthercomprising a return spring engaged between the drive plunger and thecharging handle.
 8. The lancing device of claim 1, further comprising anejector spring for biasing the ejector rod relative to the mechanismhousing.
 9. An independent drive core mechanism for a lancing device,comprising: a mechanism housing having a bore extending axiallytherethough; a drive plunger comprising a receiver for releasablyengaging a lancet, said drive plunger translationally mounted foradvancement and retraction within the bore of the mechanism housingbetween an advanced position and a retracted position; an ejector rodcomprising proximal section, a distal section and a rib for selectivelyabutting a tail of the drive plunger to prevent ejection in theretracted position, wherein the rib extends laterally from the electorrod surface between the proximal section and the distal section; a drivespring engaged between the mechanism housing and the drive plunger, foradvancing the drive plunger toward the advanced position; a charginghousing for retracting the drive plunger and energizing the drivespring; and at least one retention member for engagement with acooperating portion of an external housing.
 10. The lancing device ofclaim 9, further comprising a return spring engaged between the driveplunger and the charging housing.
 11. The lancing device of claim 9,wherein the ejector rod comprises at least one finger extending througha slot in the charging housing.
 12. The lancing device of claim 11,wherein the slot in the charging housing comprises a generally helicalsection for twisting the ejector rod relative to the drive plunger asthe finger traverses the slot.
 13. The lancing device of claim 9,wherein a laterally projecting wing of the drive plunger moves axiallywithin a slot in the mechanism housing to define a stroke of the driveplunger.
 14. The lancing device of claim 9, wherein a flexible armextending from the drive plunger releasably engages a shoulder of themechanism housing to retain the drive plunger in a retracted positionagainst the bias of the drive spring.
 15. A lancing device comprising:an external housing comprising a lancet opening; and an independentdrive core mechanism positioned at least partially within the externalhousing, said independent drive core mechanism comprising: a mechanismhousing; a drive plunger for receiving a lancet, said drive plungertranslationally mounted for advancement and retraction within themechanism housing; an ejector rod axially movable and rotatable througha bore in the drive plunger, the ejector rod comprising at least onefinger extending outwardly from the ejector rod surface; an ejectorspring for biasing the ejector rod relative to the mechanism housing; adrive spring engaged between the mechanism housing and the driveplunger, for advancing the drive plunger toward the lancet opening; anda charging housing comprising at least one slot with a length comprisinga generally helical section, wherein the at least one ejector rod fingertravels within the length of the at least one slot.
 16. The lancingdevice of claim 15, wherein the ejector rod comprises a pair ofdiametrically opposing fingers and the charging housing comprises a pairof diametrically opposing slots.